Electric vehicles driven by electric power supplied from a battery unit have prevailed in recent years. The battery is heavy in weight and cooling thereof is necessary, and place and structure for mounting batteries in the vehicles have been studied and proposed.
Conventionally, electric power is supplied to the vehicles via an overhead wire provided along the guideway. However, in a new transit system in which electric vehicles with rubber-tired wheels run on guide ways provided with guide rails, a power supply system without overhead wire is demanded from the viewpoint of simplification of the power supply system, and in the case of battery driven electric vehicle, improvement concerning structure and place of mounting batteries in the vehicle is required.
Battery location in electric vehicles including passenger cars, passenger buses, and trucks is disclosed for example in Japanese Laid-Open Patent Application No. 2004-66889 (patent literature 1) and Japanese Patent No. 3149493 (patent literature 2).
According to the patent literature 1, as shown in FIG. 20, a buttery unit 02 is mounted on a roof 03 of an electric autobus 01 driven by the battery unit at a position directly above the front axle so that loads on rear axle 05 and front axle 04 are balanced when vehicle drive devices such as an electric motor and others are mounted in the rear of the vehicle, thereby ensuring running stability and improving cooling of the batteries by air relatively flowing against the vehicle as the vehicle runs.
According to the patent literature 2, as shown in FIG. 21, batteries 010 are accommodated in an elongated duct 011 extending in longitudinal direction of the car below the seats, the elongated duct 011 is connected to an air conditioning unit 012 at its front end and to opens of the rear space in the car at its rear opening 013. Air in the car room is ingested from the rear opening 013, heated by the batteries 010, and the heated air heated by cooling the batteries 010 is introduced to the air conditioning unit 012 and heated to be supplied into the car room.
With the prior art of the patent literature 1, it is necessary to increase mechanical strength of the vehicle body including the roof 03 because heavy batteries are mounted on the roof 03, which induces a problem of increased vehicle weight. Further, height of center of gravity of the vehicle increases by mounting the batteries on the roof 03, resulting deteriorated running stability.
With the prior art of the patent literature 2, air in the car room is taken in from the rear opening 013 to be used to cool the batteries 010, therefore battery room can not be sealed from the car room, and there is fear that the car room is subjected to the influence of battery electrolyte and inflammable gas developed from the battery electrolyte.
Further, in a new transit system in which electric vehicles with rubber-tired wheels run on guide ways, the batter driven vehicle is provided with vehicle control devices and cables under the floor, and it is difficult to secure enough space for mounting batteries. In order to secure enough space for mounting batteries, it is necessary to modify vehicle construction, and design must be considerably changed from that of a conventional vehicle which is driven by electric power receiving from an outside electric power source.
Further, as the electric vehicle used in the new transit system is generally large sized as compared with passenger cars, trucks, and passenger buses, large electric power must be supplied to drive their electric motors. Therefore, large capacity of battery unit is required, total weight and volume of the batteries increase to a large extent, and large space for mounting the batteries is needed. Therefore, it is not easy to secure proper space for accommodating batteries in the vehicle.